Boiler on open vented system whoosing after pump has been replaced

[essco6]

On Friday I had my CH pump replaced, now the heating isn't working properly. The boiler fires up for a short period, there is a whooshing sound and it shuts down. The house doesn't get warm because the heating is only on for short bursts. I've bled the radiators (a few of which actually do get hot). The expansion tank looks normal and the valve opens/closes.

My plumber is away on holiday next week, any suggestions? Thanks

 

[oldbuffer]

I'd try, in this order:

a. Is pump rotating. If ordinary type, remove central screw and insert screwdriver gently to see if rotor spinning. If not, check wiring.
b. Are both pump valves fully open. Close each down then fully open. If gate valves and no resistance after many turns, spindle has sheared. Drain down / bung and replace.

(a. first as some radiators warm suggesting some, possibly convection, circulation).

 

[essco6]

Thanks very much for the reply oldbuffer.

a. Pump is rotating. If I change the pump speed I can hear the water moving through the pipes at different speeds.
b. I've closed and fully opened the valves without any problems.

Could it be a blockage or air lock in the system?

 

[Agile]

But have you bled air from the central pump screw?

If so try closing all rads except one and moving the open rad along.

Also alternate between HW and CH only a few times for a minute or so each.


Tony

 

[essco6]

Thanks Tony

I bled the pump using the big screw on the back. Only water came out.

I closed all the radiators except one, and moved the open rad along. Each radiator became hot, starting at the top. It took a while for each of the radiators to become hot all over. I then opened all of the radiators, but they still aren't all getting hot.

Should I use the programmer to switch between HW & CH, or the valve?

Dave

 

[Agile]

Programmer is fine!

It will open the valves as required.

Tony

 

[essco6]

Thanks for everybody's help. I've finally got this sorted out. There was a lot of air in the system and possibly a blockage. I had somebody come around and sort this out for me. What I didn't know was you can unplug the connector on the pump to stop it. This seems to allow the air to be vented through the automatic valve (there was quite a lot). After several hours of turning rads on and off and balancing the flow through the system everything is toasty and warm.